The present disclosure relates to a damper for damping the motion of a first object relative to a second object. More specifically the damper May be used to damp an object to be machined relative to an apparatus for machining the object.
Machining may refer to any process by which an object is cut or shaped by a controlled material removal process. Types of machining include: lathing, whereby an object is turned against a cutting tool, the principal apparatus used being a lathe; milling, whereby a cutting tool rotates to bring cutting edges against the object, the principal apparatus used being a milling machine; grinding, whereby an abrasive tool rotates to bring abrasive surfaces against the object, the principal apparatus used being a grinding machine; and drilling, whereby holes are produced or refined by bringing a rotating cutter with cutting edges at the lower extremity into contact with the object, the principal apparatus used being a drill.
A damper is used to apply a reacting force to slow a moving object. The reaction force increases with the velocity of the object. This can minimise potentially harmful vibrations to structures. A number of damping technologies exist but these have limitations including size, weight and required maintenance.
One type of damper is based on fluid motion. A force exerted on the damper by an actuator displaces fluid between reservoirs through a port. Depending on the size of the port and properties of the fluid, a certain resistance is provided to the actuator for a given velocity. However, such dampers require precise manufacture and the fluid needs to be contained and controlled. Due to the required sealing and motion of such dampers, they are prone to failure due to fluid loss and require frequent servicing.
Another type of damper is based on eddy currents. These use a magnet and a conductor which move relative to each other to induce eddy currents in the conductor. The magnetic fields of the eddy currents oppose the motion on of the magnet. Such dampers are typically large and are used in applications involving large forces. For example, such dampers are used to damp buildings in the event of an earthquake or in high speed braking systems on trains. Although reliable, these dampers are very complex and expensive.
In relation to machining, damping can be used to minimise the vibrations induced in an object being machined that result from the motion of a cutting tool. However, space limitations prevent the use of many damping technologies due to their physical size. Further, some damping technologies are not suitable for applications where the object being machined is particularly brittle, for example ceramics.